Conventionally, chewing gum base and chewing gum product have been manufactured using separate mixers, different mixing technologies and, often, different factories. One reason for this is that the optimum conditions for manufacturing gum base, and for manufacturing chewing gum from gum base and other ingredients such as sweeteners and flavors, are so different that it has been difficult to integrate both tasks. Gum base manufacture, on the one hand, involves dispersive (often high shear) mixing of difficult-to-blend ingredients such as elastomer, filler, elastomer plasticizer, base softeners/emulsifiers, and sometimes wax, and typically requires long mixing times. Chewing gum product manufacture, on the other hand, involves combining the gum base with more delicate ingredients such as product softeners, bulk sweeteners, high intensity sweeteners, and flavoring agents, using distributive (generally lower shear) mixing for shorter time periods.
As the number of chewing gum varieties has increased over time, the number of gum base varieties tailored for the various chewing gums has also increased. For instance, chewing gum products now vary in terms of sugar versus sugarless gum, standard tack versus non-tack or reduced tack gum, bubble gum versus regular (non-bubble) chewing gum, stick gum versus tab or pellet gum, and a wide variety of flavors and flavor combinations for each class of gum. The tailoring of gum bases, and the matching of gum bases to particular chewing gums, has become complex because different gum base formulations are preferred for different classes and flavors of chewing gum. The manufacturing of gum bases has also become complicated due to the large number of gum bases that must now be made.
In order to simplify gum base manufacture, gum base concentrates have been developed which contain less than all of the ingredients for a particular gum base, but which contain ingredients which may be common to a large number of gum bases. Statutory Inventory Registration H1241, issued to Synosky et al., discloses a gum base concentrate which contains about 15-25% synthetic elastomer, about 40-70% synthetic elastomer plasticizer including a terpene resin, about 10-25% wax, about 1-12% softener, and about 0-3% filler. French Patent Application 2,635,441 discloses a gum base concentrate containing up to 85% polymer in addition to mineral fillers and plasticizers. The polymer is a high molecular weight elastomer having a "numerical" molecular weight of at least 220,000 and a molecular weight "by weight" of at least 450,000.
U.S. Pat. No. 4,305,962, issued to Del Angel, discloses an elastomer/resin masterbatch formed by mixing a finely ground ester gum resin with a latex elastomer to form an emulsion, coagulating the emulsion using sodium chloride and sulfuric acid, separating the coagulated solid crumbs from the liquid phase, washing the solid crumbs, and removing the excess water.
U.S. Pat. No. 4,187,320, issued to Koch et al., discloses a two stage process for preparing a chewing gum base. In the first stage, a solid elastomer, an elastomer solvent, and an oleaginous plasticizer are combined and mixed together under high shear. In the second stage, a hydrophobic plasticizer, a non-toxic vinyl polymer, and an emulsifier are added to the mixture and mixed using high shear.
European Publication 0,273,809 discloses a gum base premix which includes at least one elastomer and at least one filler. The premix, which is made in a mill, is then divided into fragments, and combined with other gum base and/or chewing gum ingredients.